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Hanhart Syndrome

Last updated Jan. 16, 2019

Approved by: Krish Tangella MD, MBA, FCAP

Hanhart Syndrome is a rare condition that primarily affects the craniofacial region and the limbs (arms and legs).


What are the other Names for this Condition? (Also known as/Synonyms)

  • Aglossia Adactylia
  • Hypoglossia-Hypodactylia Syndrome
  • Peromelia with Micrognathia

What is Hanhart Syndrome? (Definition/Background Information)

  • Hanhart Syndrome is a rare condition that primarily affects the craniofacial region and the limbs (arms and legs)
  • People affected by this condition are often born with a short, incompletely developed tongue; absent or partially missing fingers and/or toes; abnormalities of the arms and/or legs; and an extremely small jaw
  • The severity of these physical abnormalities varies greatly among affected people, and children with this condition often have some, but not all, of the symptoms
  • The cause of Hanhart Syndrome is not fully understood
  • Treatment depends on the signs and symptoms present in each person

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Hanhart Syndrome? (Age and Sex Distribution)

  • Hanhart Syndrome is a rare congenital disorder. The presentation of symptoms occur at birth
  • Both males and females may be affected
  • Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Hanhart Syndrome? (Predisposing Factors)

The risk factors for Hanhart Syndrome may include:

  • Exposure of the pregnant mother to radiation, teratogenic medications, or hypothermia
  • Trauma or disrupted blood flow to the baby in the womb
  • Chorionic villus sampling procedures (when performed too early in the pregnancy) 

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hanhart Syndrome? (Etiology)

The exact underlying cause of Hanhart Syndrome is currently unknown. However, researchers suspect that there may be genetic and/or environmental factors that contribute to the development of the condition. To date, no specific disease-causing genes have been identified.

Possible environmental factors including:

  • Exposure of the pregnant mother to radiation, teratogenic medications, or hypothermia
  • Trauma or disrupted blood flow to the baby in the womb
  • Chorionic villus sampling procedures (when performed too early in the pregnancy) 

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

What are the Signs and Symptoms of Hanhart Syndrome?

The signs and symptoms of Hanhart Syndrome vary, but may include:

  • Small mouth (microstomia)
  • Short, incompletely developed tongue (hypoglossia)
  • Absent, partially missing, or shortened fingers and/or toes
  • Jaw abnormalities such as micrognathia, retrognathia (receding jaw), or partially missing mandible (lower jaw)
  • High-arched, narrow, or cleft palate
  • Absent or unusually formed arms and/or legs
  • Missing teeth
  • Absence of major salivary glands
  • Abnormality of oral frenula
  • Aglossia (absence of tongue, or the presence of a partial tongue)
  • Epicanthus
  • Microglossia (development of a small tongue)

Some infants with Hanhart Syndrome may be born with paralysis of certain areas of the face. If the tongue and/or mouth are affected, this can worsen feeding difficulties that are already present due to the craniofacial abnormalities listed above.

The severity of the physical abnormalities associated with Hanhart Syndrome varies greatly among affected people, and children with this disorder often have some, but not all, of the symptoms.

Based on the frequency of symptoms observed, the following information may be noted:

Very frequently present symptoms in 80-99% of the cases:

  • Aplasia/Hypoplasia of the tongue
  • Hypoplasia of the zygomatic bone
  • Micrognathia
  • Narrow mouth
  • Upper limb phocomelia (underdevelopment of the arms)

Frequently present symptoms in 30-79% of the cases:

  • Abnormality of the fingernails
  • Adactyly (absence of digits)
  • Brachydactyly (short fingers or toes)
  • Finger syndactyly (clubbing or fusing of fingers)
  • Hypodontia (absence of teeth)
  • Short distal phalanx of finger
  • Split hand
  • Telecanthus (increased space between the eyes)
  • Wide nasal bridge

 Occasionally present symptoms in 5-29% of the cases:

  • Abnormality of the cranial nerves
  • Anal atresia (absence of proper anal opening)
  • Death in infancy
  • Facial asymmetry
  • Feeding difficulties in infancy
  • Gastroschisis (when the baby’s bowels are present outside the abdomen)
  • High palate
  • Intellectual disability
  • Jejunal atresia (partial absence of stomach membrane folds)
  • Neurological speech impairment

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Hanhart Syndrome Diagnosed?

  • A diagnosis of Hanhart Syndrome is typically made based on the presence of characteristic signs and symptoms
  • In some cases, the diagnosis may be suspected before birth if concerning features are seen on ultrasound

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hanhart Syndrome?

The complications of Hanhart Syndrome may include:

  • Severe physical deformities, especially affecting the face and limbs
  • Intellectual disability
  • Gastroschisis (when the baby’s bowels are present outside the abdomen)
  • Neurological speech impairment
  • Death in infancy

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Hanhart Syndrome Treated?

Because Hanhart Syndrome affects many different systems of the body, medical management is often provided by a team of doctors and other healthcare professionals. Treatment for this condition varies because it depends on the signs and symptoms present in each person.

  • For example, limb and/or craniofacial abnormalities may be treated with surgery and/or prostheses
  • Affected children may also need speech therapy, physical therapy, and/or occupational therapy

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Hanhart Syndrome be Prevented?

  • Currently, Hanhart Syndrome is not preventable, since it may be a genetic disorder
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Hanhart Syndrome? (Outcomes/Resolutions)

The long-term outlook (prognosis) for people with Hanhart Syndrome varies and largely depends on the signs and symptoms present in each person.

  • Severe associated craniofacial abnormalities can be life-threatening and may impair breathing, eating, and/or swallowing
  • However, early diagnosis and treatment can improve survival and quality of life for affected people

(Source: Hanhart Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Additional and Relevant Useful Information for Hanhart Syndrome:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/rare-disorders/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Nov. 30, 2017
Last updated: Jan. 16, 2019